Endoscopes are well-known in the art of minimally invasive surgery for the observation of, and introduction of materials and devices to, sites inside a patient's body. For example, catheter-based devices are commonly introduced through a working channel (also known as “accessory channel”) of an endoscope to a site in a patient's body. A well-established technique, known as “long wire guide,” is commonly used for guiding a delivery catheter to a target site in a patient's body and it includes: (1) directing a steerable wire guide through a working channel to the target site; (2) retaining a proximal portion of the wire guide outside the body; (3) threading a delivery catheter, which has a wire guide lumen throughout its length, onto the proximal end of the wire guide; and (4) advancing the catheter along the wire guide to the treatment site.
One example of a desired path to a target site is the passage through a working lumen or channel of an endoscope to a biliary duct or another structure along the alimentary canal in a gastroenterological application. The catheter device may include a treatment device such as a stent or fluid-inflatable balloon disposed at its distal end for deployment at a target site (e.g., an occluded biliary duct or coronary artery). The catheter may also have a tool such as a cutting wire or cutting needle disposed at or near its distal end (e.g., a papillotome, sphincterotome, etc.), or the catheter may have an aperture for the delivery of a fluid through a second lumen (e.g., radio-opaque fluid for contrast fluoroscopy, adhesive or gelling agent for delivery to a target site, etc.).
Procedures that employ wire guides may require exchange of treatment appliances. For example, a balloon catheter may be replaced with a stent deployment catheter. In a typical application of such a procedure, a balloon catheter is directed to the site of a stenosis (e.g. in an artery, biliary duct, or other body lumen) as described above. Fluid is then used to inflate the balloon so as to dilate the stenosis. Some procedures are effectively concluded at this point. However, many procedures follow dilation of the stenotic stricture with the placement of a stent to maintain patency of the reopened lumen. This may require that the balloon catheter be withdrawn to allow for the introduction of a stent-deployment catheter (unless a stent placement catheter with an internal/placement balloon is used to accomplish both stenosis-dilation and stent-placement). It is preferable that the wire guide remain in place for guidance of the stent-deployment catheter without having to re-navigate the wire guide back into to the newly reopened lumen.
In order to prevent undesired displacement of the wire guide, any exchange of long wire guide catheters requires that the proximal portion of the wire guide extending out of the patient's body (or endoscope, depending on the entry point for the desired path to the target site) be longer than the catheter being “exchanged out,” so that control of the wire guide may be maintained as the catheter is being removed. Likewise, the wire guide must be grasped while the entire catheter being “exchanged in” is threaded onto it and directed along the desired path to the target site. In other words, for the operating physician and assistant to be able to hold the wire guide in place while removing one catheter for replacement with another, each of the catheters must be shorter than the portion of the wire guide that is exposed outside the patient's body (and, if used, outside the endoscope). Put another way, the wire guide must be about twice as long as a catheter that is being used over that wire guide. Additionally, in the case of gastrointestinal endoscopy, even more wire guide length is necessary. This is because the shaft of the endoscope through which the wire guide and catheters are placed must have a length outside the body for manipulation and control, and the catheter itself must have some additional length outside of the endoscope for the same reason. As those skilled in the art will appreciate, wire guides having the necessary “exchange length” are cumbersome and difficult to prevent from becoming contaminated.
An alternative technique for guiding a delivery catheter to a target site in a patient body utilizes catheters having a relatively short wire guide lumen in catheter systems commonly referred to as “rapid exchange,” “short wire guide,” or “monorail” systems. In such systems, the wire guide lumen extends only from a first lumen opening spaced a short distance from the distal end of the catheter to a second lumen opening at or near the distal end of the catheter. As a result, the only lumenal contact between the catheter's wire guide lumen and the wire guide itself is the relatively short distance between the first and second lumen openings. Several known advantages are conferred by this configuration. For example, the portion of the wire guide outside the patient's body may be significantly shorter than that needed for the “long wire configuration.” This is because only the wire guide lumen portion of the catheter is threaded onto the wire guide before directing the catheter through the desired path (e.g., a working lumen of an endoscope, an endoluminal passage, etc.) to the target site.
Similarly, during endoscopic procedures, there is sometimes a need to exchange the endoscope being used. For example, a physician may desire to exchange a side-viewing endoscope for an end-viewing endoscope, with the endoscope being “exchanged in” directed to a particular location where a wire guide or catheter device is already in place. Currently, such an exchange must be effected in a long-wire type of operation wherein, after the first endoscope is removed, the second endoscope is fed along the entire length of the wire guide or catheter device to the desired location, with that tracking through a working channel. As described above with reference to long-wire procedures as used with catheter devices, his maneuver requires that the wire guide or catheter device be very long (commonly >300 cm) so that the entire endoscope can be directed along it without losing the ability to hold onto at least one point of the wire guide or catheter device outside the patient's body. Such long devices pose difficulties in proper handling that prevents damage or contamination, sometimes requiring an extra person to hold the extra length.
Therefore, it would be advantageous to provide an endoscope and/or accessory thereto that would allow a user to utilize a short-wire type of operation, benefiting from the advantages of time and economy of motion presented thereby.